Method of treating impure molten metals



\ A ril 27,1926. I 1,582,037

H. HARRIS Q METHOD OF TREATING IMPURE MOLTEN METALS Filed April 26, 1924 4 Sheets-Sheet 1 April 27 1926.

H. HARRIS METHOD OF TREATING IMPURE MOLTEN METALS Filed April 26, 1924 4 Sheets-Sheet 2 April 27 1926.

H. HARRIS,

METHOD OF TREATING IMPURE MOLTEN METALS 4 Sheets-Sheet 5 Filed April 26, 1924 anventoz April 27 1926.

H. HARRIS METHOD OF TREATING IMPURE MOLTEN METALS Filed April 26, 1924 4 Sheets-Sheet 4 v anon Roz UNITED STATES PATENT OFFICE.

.- HENRY nannrs, or LONDON, ENGLAND.

METHOD OF TREATING IMPURE MOLTEN METALS.

Application filed April 26, 1924. Serial No. 709,088.

To all whom it may concern:

Be it known that I, HENRY HARRIS, a subject ofthe King of Great Britain, and resident of London; England,' have' invented certain new and useful Improvements in' Methods of'Treatjng Impure Molten Metals,

of which the following is a specification.

This inventionrelates to improvements in treatin molten metals (and by the term metals l include alloys) and more particle larly to a method of treating impure molten metals with a' reagent.

The apparatus hereinafter described for carrying out the method forms the subject matter of my co-pending application Serial No. 709,089 filed on even date herewith.

In certain known processes for the treatment of impure molten metals to eliminate one or more of the impurities or alloying elements, the molten metallic mass is treated with a molten reagent or reagents which act upon or absorb or otherwise become associated with the contained, impurities such as copper, zinc tin, arsenic, antimony,

bismuth and 'the like. As illustrating prior process of the character in question reference maybe made to the specification of my co-pending application Serial No. 568,632, filed June 15, 1922, wherein as one example a molten mixture of caustic soda and sodium chloride with a suitable oxidizing reagent such as nitrate of sod'ais used.

as the reagent for treating molten lead. In carrying out such processes it is .very

important if not necessary from an economic standpoint to recover the reagent or reagents from the resulting mixture or mass containing the reagent and impurities. To accomplish this recovery the mixture must 'be dissolved or brought into a state of solution as with waterand .the solution of the reagent or reagent mixture, as the case may he, must be separated from the impurities,

' after which in order to get the reagent into form for further use as a molten reagent,

the solution must be evaporated to substantial dryness and then fused.

' This evaporation is costly due to theexpensive apparatus required and the large amount of space occupied by the same, the cost of conducting the operation and the time required. Also the use of a molten reagent requires apparatus for heating same. The. objects of the present invention are to obviate these expenses and objections inherent in the use of a molten reagent and the use of a solution of a reagent or of a mixture of reagents for the treatment of the molten metallic mass. The molten metal and regeant are brought into intimate contact one with another. The molten metal may itself be utilized to evaporate the water of the solution either directly by bringing the two materials into direct content, or indirectly as by causing the molten metallic mass to heat a vessel into which the solution is passed, and preferably into which the molten metal is admitted. Alternatively such vessel may be heated otherwise as for example by the heating medium used to keepthe 1netallic ma'ss molten. In any case the evaporated water in the form of steam or a part of it may be utilized to bring about in suitable manner intimate contact or intermingling of the reagent and molten metal. The spent reagent carrying the impurity or impurities from the metallic mass may then be recovered in molten semi-molten or solid form as the case may be. This regeant mixed with impurity may then be brought into solution in known in the form of a solution and again used for another refining operation without being Yr dried or fused. r

The process thus not only eliminates the cost and delay incidental to the usual evaporating procedure but it also makes it possible to utilize the heated molten metallic mass to evaporate the water from the reagent solution and utilize the generated steam in the process. It, also permits the use of a regeant which is soluble but not readily fusible at temperatures at which metals can be efficiently refined or separated.

I will describe by way of illustration some examples of how the invention may be carried out. w

I use in solution form a regeant mixture comprising caustic soda, sodium chloride and a suitable oxidizing agent such as nitrate of soda, which I have heretofore used in molten form. This solution is then brought into intimate contact with the molten metallic mass to be refined, say impure molten lead, by having the molten lead kept at a temperature which may be less than 500 C. and forcibly injecting the solution into the lead relying upon the generated steam to force the reagent particles through the mass of the lead, with or without additional stirring. Or as above stated the solution may be fed under pressure into a vessel into which the molten metal is also admitted, and the pressure of steam generated by evaporation of the solution, utilized to force the molten metal and dehydrated reagent out through a pipe in which they will be intimately intermingled. If desired the pipe may lead to a reagent pot sealed at its lower end by the metal, in which case the metal may be repeatedly passed through the vaporizer and reagent pot; as hereinafter described.

It will be understood that so far as concerns the process any suitable form of apparatus may be utilized to efi'ect the desired mixing of the soluble reagent and molten metal having due regard to the fact that the molten metal is of much greater specific gravity than the reagent solution.

In the particular example just given any other suitable reagent may be used in solution such for example as the othersmentioned in the specification of my said 00- pending United States application Serial As further examples of the reagent mixture used by me I may mention for instance in the clecoppering oflead as one example,

the use of a solution of alkali sulphide or of sulphur dissolved in caustic alkali. As

another example I may use for the dezineing of lead a solution of zinc chloride and sodium chloride with or without a suitable oxidizing agent deliberately added to assist the natural oxidizing action of the air to which access is given. w

While I have given concrete examples a to the treatment of -molten lead by the use of reagents in solution, I do not wish to be understood as limiting my invention in its broader aspects to the treatment of lead by reagent in solution as the invention may be useful in thetreatment of other molten metals such for example as copper, tin,-etc.

It will be seen from the foregoing description' of the invention that; by the use be able to conduct the operations at temperatures at which some reagents donot fuse,

ing description and drawings of apparatus specially useful in carrying out the process. Apparatus,

Referring to the drawings, Figure 1 is a diagrammatic sectional elevation of a pot containing a molten metallic mass into which a reagent solution delivery pipe extends.

Figures 2 and 3 are diagrammatic sectional elevations of two further arrangements in which provision is made for controlling and utilizing the steam evolved from the reagent. solution.

Figure 4 is a somewhat diagrammatic sectional elevation of a complete apparatus operative in accordance with the present invention, Figure 5 being a similar view with certain parts raised and Figure 6 being a plan view illustrating in particular the power transmission mechanism for the moving parts.

In Figure 1 of the accompanying drawings the reagent solution is delivered into direct contact with the molten metallic mass in the pot 1 through the open-ended pipe 2 having its free end immersed to a suitable depth below the level of the molten metallic mass. The steam generated by the contact of the reagent solution with the molten metallic mass spreads throughout the latter in In the modified form of apparatus shown in Figure 2 the heat of the molten metallic mass is utilized for vaporizing purposes indirectly by causing it to heat a vaporizing element which in turn parts with its heat to 1 the reagent solution. In the construction illustrated I immerse or partly immerse a vessel or chamber 3 in the molten metallic mass in the pot 1 and I force the reagent solution preferably in sprayed form into it through the pipe 2. The steam liberated by contact of the solution against the hot walls of the vessel 3 or against a splash plate 3 or the like therein, creates internal pressure *which can be regulated by outlet pipes {l and valves 5 and thus utilized to force the reagent in dehydrated form out of the vessel and into contact with the molten metallic mass. l

The reagent may be forced out through a .hole or outlet valve 6 in the vessel 3 beneath case the reagent withor without entrained molten mass, and the particles of the dehy drated reagent will be caused to intimately intermingle with the molten metal throughout the mass of the same, to bring about the desired reactions in the metal for the purification or other change in the condition of the same. Alternately as shown in Figure 3 the vessel may have no outlet below the molten mass, so that the steam under pressure in the vessel must force the reagent up an exit pipe 7 extending to a-more con= venient spot for the reaction, as for example .into a reaction chamber 8 in which the molten ,metallic mass may be circulated through the reagent collected in it by suitable means. If desired the vessel 3 although having no submerged outlet may have a submerged inlet or inlet valve 9 so that the molten metallic mass will periodically well up into the interior of the vessel and be carried over with the reagent according to the general principle of operation of the well known Roesing pump,thereby obviating the necessity of using a separate pump or the like to circulate the molten metallic mass through the reagent or at least supplementing the effect of such ump. As is well understood by those skil ed in the art, such a pump operates on the principle of admitting fluid into the compression chamber until the level of the fluid in the chamber rises above a certain-outlet passage whereupon pressure in the chamber, which may be brought about by admission of compressed air or the like, closes the valve in the inlet port and forces the fluid out of the chamber through the outlet orifice until the level of the fluid recedes below the outlet orifice whereupon the pressure of the impelling air or other medium ip the chamber is reduced and the inlet valve again opens to admit more of the fluid to be pumped until the fluid again rises to the level of the outlet orifice, whereupon the pressure again causes it to be discharged through the outlet orifice, and so on.

Instead of leaving the steam pressure to relieve itself periodically by passing up the exit pipe 7, a rotary ported valve or slide valve or the like (hereinafter described) on the steam outlet pipe 4 or elsewhere, may

be provided to permit periodic escape of the steam so that the molten metal will periodically well up into theinterior of the vessel without necessitating the depression of the liquid level therein as far as the level of the mouthof the exit pipe.

lVhi'chever constructional form of apparatus is preferred the steam produced can be conveyed to a condenser or'use'd for heating purposes or a part of it maybe conducted through a pipe 10 (Fig. 3) to be utilized as a jet to agitate or cause circulation in potl of the molten metallic mass to keep itstemperature uniform. It is to be understood,

however, that I do not confine myself to this particular method of agitating the molten metallic mass which may for, cxaniple be.

and preferably is agitated mechanically, as hereinafter described.

In the. complete apparatus as shown in Figures 4, 5 and 6, I utilize the steam generated in the vaporizing vessel 3 by the heated 'molten metallic mass, to force the molten metal and the reagent (which due to the heat may now be in a fused form) up the exit pipe 7 into an open ended cyl- 'inder 11 surmounting a pot 12 provided with an automatic inlet valve 13 or other suitable valve at its base and a trap or metal seal 14 which prevents the escape of reagent (which may only partially be spent) from cylinder 11 into pot 1, and allows the metallic mass (which may only partially be refined) to pass back freed from reagent, which remains in the cylinder, into the pot 1. In this way the metallic mass is brought into very intimate contact with the trapped reagent which is sealed at its lower end by the molten metal, and may be repeatedly circulated through the reagent by way of the vaporizing vessel 3 up the discharge pipe 7 along with some of the reagent and into the adjacent cylinder 11 now containing reagent,

and thence into pot. 12'and back to the pot 1, until all the metal in the pot 1 has been refined or attained a desired'condition.

. This repeated circulation enables a very efficient purification of the molten metallic mass to take place. Moreover, the purification can be effected fractionally by removing the reagent from time to time and introducing fresh batches of the reagent solution, or solutions of different reagents, and if necessary by altering the physical "conditions somewhat as by a change of temperature. In this way the most easily separated impurity can beremoved first substantially uncontaminated with other impurities, which latter can be similarly separated in succession.

In the constructional arrangement of the apparatus shown in Figures 4, 5 and 6, the vaporizing vessel or flash aboiler 3 and the reagent cylinder 11 constitute the main elements of a single unit movable from place to place by overhead means such as the crane I 15.' This unit also comprises a horizontal frame 16 integral with a vertical frame 17 and is firml held in position on the pot 1 by holding own screw hooks 18. The molten metallic mass to be refined is contained. in the pot 1 set in a furnace substantially as described in my United States Patent No. 1,465,128, granted August 14, 1923.

The vaporizing vessel 3 is shown provided at its base with two inlet ball or other suitable valves 9 designed to allow of the entry only of metal and with jets 19 set; in a 'et ring 20 or, other suitable distributing device for conducting or spraying the reagent solution onto the walls of the vaporizer 3. The reagent is delivered tothis ring by any suitable connection. To assist in the spraying either compressed air or steam may be used. The mixture of metal 'and reagent forced through the pipe 7 is delivered into the reagent cylinder 11 and pot 12 by a. distributor 21 which may be designed to split up the mixture into thin streams or fine drops.

The valve 13 in'the base of the metal seal pot 12 enables the molten metallic mass to pass into the pot when the apparatus is lowered into the molten metal bath, and is adapted to be closed when lifted out of the metal. The valve is mounted on an arm or lever pivoted at 13 and this lever is provided on the opposite side of the pivot from the valve member, with a weight 13 shown in the form of a ball. When the pot is being immersed in the molten metal the buoyant force of the molten metal on the ball weight will counteract the force of gravity on the ball and cause the arm to swing upward on its pivot to open the valve and allow metal to flow from the pot 1 into the metal seal pot 12 until it.reaches the level of the metal in the pot 1. When it is desired to lift the 0t 12 from the pot 1, as the pot is being ifted the valve will again close due to the presence of metal in the metal seal pot 12, in time to prevent any molten reagent that may be in cylinder 11 from passing out through the valve into the pot 1.

During a refining operation further quantities of metal are delivered into pot 12 from the vessel 3, but it overflows through the port 22 of the metal seal or trap 14. The overflowing molten metal passes back unmixed with reagent into the pot 1 leaving the reagent, which is of less density, in the cylinder. 11 where it floats onthe surface of the metal trapped in pot 12. I may provide the port 22 of the pot 12 with a metal seal screw valve (not shown) operated from any convenient position outside the apparatus, so that, when I desire to remove the reagent contained in the cylinder 11 instead of removing the cylinder 11 and its pot 12 bodily from the apparatus, for which provision is made, and then pouring out the reagent, I may partially or entirely close this screw valve, thus preventing a portion or the whole of the metal from the flowing out of the outlet port 22 into the pot 1. with the result that the level of the metal,

which continues to flow into the cylinder 11 will rise forcing the molten reagent (which owing to its lower specific gravity floats on the surface of the metal) to overflow from the cylinder 11 over a suitable spout 11 (Fig. 6) into a portable receptacle.

Operating in the cylinder 11 and pot '12 through shaft 27 stirrers- 28 which serve to 1 stir the molten metal in the-bath l sd'as continually to present fresh and hotter molten metal to the external surface of the vaporizer 3. This motor also drives a rotating piston valve 29 which serves, when it is open, to allow of the escape thrcugh a separator 30 of the steam generated by evaporation of the reagent solution in the vaporizer 3. The separator 30 is designed to return to the vaporizer any reagent solution entrained with the steam.,

The valve 29 has a variable opening which can be regulated during operation and is automatically rotated, its speed of rotation being regulated by a radially shiftable friction disc drive 31.

- Some parts of the apparatus which are above the metal bath may be enclose-l in a casing 32 which serves, when necessary, to heat the separator 30 and the cylinder 11 by means of the waste furnace gases For, by opening the damper 33 and closing the damper 34, the furnace gases are conducted from the flue 35 up the inlet flue pipe 36 of the apparatus round the interior of the easing 32 and are drawn through the outlet flue pipe 37, in the direction of the arrow shown in Fig. 4.

Should I not desire thus to heat the apparatus, I may close the inlet flue damper 33 and open the damper 34, when the gases will pass directly from the flue 35 into the main flue as shown by arrows in Fig. 5.

Operation.

Incarrying out for instance a refining operation by the use of the complete apparatus above described, assuming that the molten metallic mass to be purified is in the pot 1' and that the movable unit is in the raised position shown in Fig.- 5:

\ The rotary piston valve 29 is set full open and the movable unit is lowered, whereupon the molten metallic mass rises in vaporizer 3 until it reaches the level of the metal in suitably sprayed into the vaporizer 3 under a pressure which maybe greater than that of the internal pressure mtended to be generated in the vaporizer. The solut1on is evaporated due to contact with the walls of the vaporizer heated by the molten metallic the vaporizer, and steam leaves the appa-' ratus by way of the outlet port of the valve. If the valve 29 be kept closed, the pressure of steam generated in the vaporizer forces the molten metallic mass with dehydrated reagent up exit pipe 7' until theliqui level in the vaporizer reaches just below that of the bottom end of the said pipe 7 through which the steam can then escape relieving the pressure within the vaporizer and allowing the molten metallic mass to again rise through the inlet valve 9 thereby preventing for the time further esca e of steam and causing another increase 0 pressure within the vaporizer, whereupon the molten metal with dehydrated reagent and steam is again forced up the exit pipe. Thus with valve 29 remaining closed, the intermittent pumping in rapid pulsations of metal from the pot, through valve 9 and up the exit pipe 7 together with dehydrated reagent and steam into the cylinder 11 continues so long as the generation of steam in the vaporizer is maintained.

In most instances however in the refining of metals it is necessary to be able to limit or even prevent the escape of steam mixed with the stream of metal and reagent issuing from the delivery pipe; This object is attained by revolving the piston valve 29 so as to permit of the escape through it of any desired proportion of the steam generated in the vaporizer for prearranged intermittent periods of time. Through adjustment of the action ofthis valve 29, which ad'ustment can be efiectedwhile the valve is in rotation,'the variation of the level of the dehydrated reagent and metal in the vaporizer,

. which depends upon variations of the internal pressure of steam, can be controlled so that if necessary the level never falls to a point at which steam can leave the vaporizer through the exit pipe 7 the end of which can be kept continuously sealed by metal and dehydrated reagent, metal entering the vaporizer through the valve 9 at its base when the piston valve 29 is open and the metal and. reagent being ejected only when the valve 29 is closed, any excess pressure of steam being removed by means of a relief valve (not shown).

The valve 29 is preferably so adjusted and.

' operated, that the level of the metal, upon which the reagent floats, is maintained at a little above the level of the pipe opening, so that some metal and reagentiwill be continuously forced out together, but even if this 'is not exactly maintained, the fluctuations in the level can be so controlled that the reagent and metal are respectively forced into the pipe at such rapidly recurring short valve may be provided in the exit pipe 7 near its lower end to support the column of liquid therein. f

In passing into the cylinder 11 owing to its considerably superior specific gravity the molten metallic mass is separated from the reagent, which remains floating on the top of the molten metal in the metal seal pot 12 through which the metal passes, rises through the siphon trap 14 and emerges from-the outlet port 22 returning to pot 1. The pot 12 itself remains full of metal, at least to the level of the 'outlet port 22 and forms an efficient seal for the supernatant reagent.

When the cylinder ll becomes full of reagent, it may be emptied by means herein before described'and the contents treated for the recovery of the reagent solution for further refining operations and for the impurities which have been absorbed from the metal being refined or separated from'its alloying elements.

In certain cases I may arrange during the course of the operation to feed automatically into the cylinder ll additional substances in a dry molten or gaseous state.

While I have described my invention according to certain particular ways in which the method may be practiced, and in connect1on with certain apparatus suitable for carrying out the same, it will be obvious to those skilled in the art, afterunderstanding the invention, that various changes and modifications may be made in the manner of practiclng the invention to better suit it to different metals and conditions, and I do not wish to be understood as limiting myself to the particular manner of practicing the invention as herein described, but aim in the appended claims to cover all changes and modifications as may come within the scope of the invention. v In the specification and appended claims I use the terms molten metal and impurities for brevity and succinctness, but in a broad sense. I wish to be understood by the term molten metal as including molten al- What I claim as new and desire to secure by Letters Patent, is:

1. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises using the reagent in solution form, heating the same to bring the reagent intoa physical state suited to the desired reaction and to generate animpelling pressure and intermingling said heated reagent and molten metal utilizing said ressure to effect or assist in effecting said' the reagent with the molten metal.

intermingling.

2. Process of treating molten metal with a reagent for removal of one or more 1mpurities, which comprises using the reagent in solution form, heating the same to bring the reagent into a physical state suited to the desired reaction and to generate an impelling pressure and intermingling said heated reagent and molten metal, utilizing said pressure to impel the reagent and molten metal together along a passage.

3. Process of treating molten metal with a reagent for removal of one or more impuri ties, which comprises using the reagent in solution form, utilizing the heat of the molten metal to evaporate the solution and generate an impelling pressure, and intermingling said heated reagent and molten metal utilizing said pressure to effect or assist in effecting said intermingling.

4. Process of treating molten metal with a reagent for removal of. one or more impurities, which comprises as a step using r the reagent in solution form, and utilizing the heat of the molten metal to heat the reagent so as to evaporate water therefrom and thus bring the reagent into a physical state suited to the desired reaction.

5. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises using the reagent in solution form, utilizing the heat of the molten metal to heat the reagent so as to evaporate water therefrom and thus bring the reagent into a physical state suited to the desired reaction and to generate an impelllng pressure and intermingling said heated reagent and molten metal utilizing sald pressure to effect or assist in eflecting said intermingling.

* 6. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises as a step bringing the reagent insolution form into contact wlth the molten metal utilizing the heat of the molten metal to heat the reagent so" as to evaporate water therefrom and thus bring the reagent into a physical state suited to the desired reaction. I

7. In the cycle process of treating molten metal with a reagent for the removal of impurities therefrom and the subsequent recovery of the reagent from a mixture contaming said reagent and impurities, for use with another batch or batches of metal to be treated, the step which consists in converting the reagent from solution form to a molten form by bringing the reagent in solution form into contact with molten metal.

8. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises bringing the reagent in aqueous solution into contact with the molten metal and utilizing the pressure of the evolved steam to effect intermingling of 9. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises introducing a solution of the reagent into a vaporizing vessel in which the reagent is heated to evaporate water therefrom to partly or wholly dehydrate the reagent, utilizing the pressure of the steam generated in said vessel from the solution to discharge the partly or wholly dehydrated reagent from said vessel and intermingling said reagent and molten metal.

10. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises introducing a solution of the reagent into a vaporizing vessel into which the molten metal is being admitted and causing the pressure of the generated steam to force out the molten metal and reagent.

11. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises as a step introducing a solution of the reagent into a vaporizing vessel where it is partly or wholly dehydrated and causing the pressure of the generated steam to periodically force out the contents of the vessel 12. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises introducing a solution of the reagent into a vaporizing vessel into which the molten metal is being introduced and discharging from the vessel during short recurring intervals the molten metal and the reagent by the use of the steam generated from the solution in the vessel.

13. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises introducing a solution of the reagent into a vaporizing vessel into which the molten metal is being introduced,

a reagent for removal of one or more impurities, which comprises introducing a solution of the reagent into' a vaporizing vessel into which the molten metal is being introduced, utilizing the pressure of the steam generated from the solution in thevaporizer to force out the metal and the reagent, and so regulating the pressure in the vaporizer as to prevent the escape of any substantial amount of steam along with the metal and reagent.

15. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises introducing a solution of the reagent into a vaporizing vessel into which the molten metal is being introduced, and intermittently increasing and decreasing the pressure of the steam generated from the solution in the vaporizer so as to efiect, during short rapidly recurring intervals, the admission of the molten metal to the vapor-. izer and the discharge therefrom of molten metal and reagent, the period of admission alternating with the period of discharge.

16. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises introducing a solution of the reagent into a vaporizingves- .s'el immersed in the molten metal and into which vaporizer the molten metal is being generated from the solution in the vaporizer. so as to effect,.during short rapidly recurring intervals, theadmission of the molten metal to the vaporizer and, the discharge therefrom of molten metal and reagent, the

period of admission alternating with the period of discharge.

17. The process of treating molten metal with a reagent for removal of one or more impurities, which comprises using the reagent in solution form, heating the same to bring the reagent into a physical state suited to the desired reaction and to generate an impelling pressure and utilizing said pressure to impel the reagent and molten metal together along a passa'getointermingle one with the other to facilitate the reaction, passing the molten metal and reagent into a reactlon container where the reagent is retamed and the .metal brought into intnnate contact with the body of retained reagent and thence discharged.

"18. Process of treating molten metalwith a reagent for removal of one or more impurities, which comprises introducing asolutlon of the reagent into a vaporizing vessel heated by the molten metal to bring the reagent into a, physical state suited to the desired reaction and to generate an impelling pressure, utilizing said pressure, to-impel the reagent and molten metal together along a passage, and passing the reagent and molten metal into a reagent container sealed at its which thereagent in solution is introduced,

utilizing the generated steam to force the molten metal and reagent from said chamber into a. reaction container sealed at its lower end by some of the molten metal and in which container the molten reagent is collected, whereby the metal flows through the reagent in this container, and continuing the circulation of the metal through the vaporizer and reagent container until the desired condition is reached.

20. Process of treating molten metal with a reagent for removal of one or more impurities, which comprises introducing the reagent in solution into a vaporizing chamber immersed in molten metal, utilizing the generated steam in said chamber to control the admission of molten metal to said chamber and. to effect and control the discharge of molten metal and reagent together from said chamber into a reagent container having its lower end sealed by some of the molten metal and collecting the reagent in said container 'while passing themetal through the reagent and out of the container, and continuing the irculation of the metal through said vaporizer and container until the desired condition thereof is obtained.

21. In the cyclic process of treating molten metal with a reagent for the removal of impurities therefrom and the subsequent recovcry of the reagent in solution form from a mixture containing said reagent and impurities, for use with another batch or batches of metal to be treated the applying of said re covered reagent in solution form to the treatment of said other batch or batches.

22. Process of treating molten metal with a reagent for removal of one or more impurities which comprisespassing the reagent in solution form into a vaporizing chamber immersed in the molten metal, utilizing the head of molten metal to feed the same into the vaporizing chamber and utilizing the pressure generated by vaporizing the solution in the chamber to eject the molten metal and reagent from the chamber.

In testimony whereof I have signed my name to this specification.

HENRY HARRIS. 

